so its a penny and a half dollar that will give you $0.51 so you can do this
starting with your 51 pennies you can get rid of every 5 pennies and replace them with a nickel so say you get rid of 10 pennies you would have 2 nickels
so 51/5= 10.2
or 10 nickels
so that is ten combos right there along side 51 pennies
so no you do the dimes witch for every 10 pennies you get rid of is = to 1 dime so 51/10=5.1 or 5 dimes so that gives you 5 more combos
so now its 1 penny combo with 10 nickel combos with 5 dime combos
now for quarters for every 25 pennies you get rid of is = to 1 quarter so
51/25=2.04 or just 2 and with half dollars ( they do make thoses ) it is for every 50 pennies you get rid of is = to one half dollar ( which is 50 cents) so 51/50= 1.02 or 1 so it is
1 penny combo + 10 nickels combos + 5 dime combos + 2 quarter combos + 1 half dollar combo =
1+10+5+2+1=19 different sums of money